JPH02216440A - Alcohol concentration measuring instrument - Google Patents

Abstract

PURPOSE:To make the outputs of a resistance type alcohol sensor into one value having good linearity over the entire area by outputting a prescribed alcohol concn. signal when the voltages detected respectively by the resistance type alcohol sensor and an indirect type alcohol sensor satisfy required conditions. CONSTITUTION:The voltages detected according to the alcohol concn. by the indirect sampling type alcohol sensor 1 and resistance type alcohol sensor 10 in an alcohol soln. are supplied to an arithmetic unit 11 for the alcohol concn. The prescribed alcohol concn. is computed while reference is made to a memory device 12 regardless of the voltage detected by the sensor 10 when the voltage detected by the sensor 10 attains the value larger than the prescribed standard value and the voltage detected by the sensor 1 attains the value smaller than the prescribed reference voltage, by which the output of the resistance type alcohol sensor is made into one value having the good linearity over the entire area. The alcohol concn. is thus measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an alcohol concentration measuring device for measuring the alcohol concentration in a liquid containing alcohol.

(Prior Art) Recently, in various countries, alcohol-mixed gasoline, which is a mixture of alcohol and gasoline, has been used as so-called "gasohol." Naturally, the octane number will change between genuine gasoline and gasohol mixed with alcohol, so the fuel injection amount and ignition timing of the engine will also differ, so the engine is equipped with an alcohol-mixed fuel.

Here, looking at the basic injection amount TP when using genuine gasoline, the intake air flow is Q, the engine speed is N,
When the constant is k, the basic injection amount TP is calculated as TP = KxQ/N (1). Then, the basic injection amount TP is corrected based on signals from various sensors such as a water temperature sensor and an oxygen sensor, and various switches such as an engine switch and a throttle valve switch, and finally the fuel injection amount T by the injection valve is determined by T+ = Tp Xα×α′XC(III-F +
Ts-*.(2), α: Air-fuel ratio feedback correction coefficient α': Basic air-fuel ratio learning correction coefficient C0EF: Various correction coefficients T, : Calculated as battery voltage correction coefficient. At this time, the air-fuel ratio feedback correction coefficient α is corrected based on the oxygen concentration signal from the oxygen sensor, and the basic air-fuel ratio learning correction coefficient α is corrected based on Tp and engine speed N for basic injection. The fuel ratio (air to fuel ratio) A/F is controlled to be 15:l.

In this way, the air-fuel ratio A/F of genuine gasoline is 15:l, or the air-fuel ratio of alcohol-mixed gasoline has the characteristics as shown in Figure 6, and when the alcohol concentration is 100%, the air-fuel ratio is 6.l. It is known that it will become.

Therefore, when using alcohol-mixed gasoline,
From equation (2), calculate the fuel injection amount T1, T'=CK x TP
xα×α'X COF:F + T s ”” (
3) It is necessary to calculate co = a constant determined by the alcohol concentration.

Here, as an alcohol sensor for detecting the alcohol concentration in alcohol-mixed gasoline, a resistance-type alcohol sensor that detects the alcohol concentration from the specific resistance value that gasoline and alcohol have is being considered. As shown in Fig. 7, this resistance type alcohol sensor has a pair of electrodes S and C disposed facing each other with a predetermined distance apart in the middle of a pipe A serving as a flow path, and one interposed between the electrodes S and C. Based on the fact that the resistance value decreases as the alcohol concentration of the alcohol-mixed gasoline d increases (see Figure 8), the electrodes S, C and the voltage detection resistor e are connected in series to the DC power supply f, and the voltage detection resistor e The alcohol concentration is detected from the change in the output voltage vs derived from .

In other words, as the alcohol concentration C increases, the resistance value of the electrodes S and C decreases. However, below the alcohol concentration C or low concentration range, the output voltage Vs is controlled by the resistance of gasoline, so the detection voltage hardly changes. For some reason, the output voltage vs suddenly decreases, so the output voltage V8 of the resistive alcohol sensor has the voltage characteristics shown in FIG. 9 with respect to the alcohol concentration C.

(Problem to be solved by the invention) By the way, in general, in electrolyzers, are there ions in the electrodes?
It is widely known that the polarization effect produced by the product of S and the relaxation effect that resists the movement of ions appear.Resistance alcohol is a method in which a pair of electrodes C and C are immersed in alcohol-mixed gasoline D and then energized. In sensors, when the alcohol concentration increases, the polarization effect and relaxation effect cause the electrode to
A phenomenon occurs in which the electrical conductivity of c is lost and reduced.

Therefore, when the alcohol concentration C increases, the output voltage Vs across the voltage detection resistor e should increase, but due to the polarization effect,
Due to the relaxation effect, the output voltage v3 decreases in a region where the alcohol concentration C is high.

Thus, as shown in FIG. 9, the output voltage vs across the voltage detection resistor 0 has a maximum value vs□ when the alcohol concentration is high, for example, when the alcohol concentration C=90%. Therefore, if the output voltage vs when one alcohol concentration C = 100% is taken as the reference voltage value VSO, then for the same alcohol concentration C, the corresponding group ? In a region larger than the F-voltage value Vso, the output voltage vsl has two values, and there is a problem that the alcohol concentration C cannot be measured accurately.

Thus, in the resistive alcohol sensor according to the prior art, the output voltage Vs is based on ? Fi voltage value Vs. There is a drawback that only the following output voltage v32 can be used as a measurement result, and the range of use of the measurement result is narrow.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and uses a resistive alcohol sensor in combination with an indirect sampling type alcohol sensor that measures alcohol concentration from the potential difference between a pair of electrodes. The present invention provides an alcohol concentration measuring device whose results can be widely used.

(Means for Solving the Problems) The means of the present invention configured to solve the above-mentioned problems is such that the devices are arranged facing each other at a distance in an alcohol mixed liquid, and a constant voltage or current is applied thereto. It has a pair of current-carrying electrodes and a pair of detection electrodes located between the pair of current-carrying electrodes and facing each other with a predetermined distance between them. an indirect sampling type alcohol sensor that detects the alcohol concentration; a resistance type alcohol sensor that detects the alcohol concentration from the resistance value in the alcohol mixed liquid; a first determination means for determining whether or not the alcohol concentration is smaller than a first reference voltage value when the concentration is high; and a second determining means for determining whether or not the detected voltage of the resistive alcohol sensor is greater than a second reference voltage value set in advance as a reference, and the first determining means determines whether the detected voltage of the resistive alcohol sensor is greater than the reference voltage value of the ff1l. If it is determined that the voltage is lower than the first reference voltage value, the alcohol concentration is calculated using the detection voltage of the resistive alcohol sensor, and the first determination means determines that the detected voltage of the resistive alcohol sensor is greater than the first reference voltage value. When it is determined that the detection voltage of the indirect sampling type alcohol sensor is larger than the second reference voltage value, the second determination means determines whether the detected voltage of the indirect sampling type alcohol sensor is larger than the second reference voltage value, and when it is determined that the detection voltage of the indirect sampling type alcohol sensor is larger than the second reference voltage value, the resistance type alcohol sensor The alcohol concentration is calculated based on the detection voltage of the resistance type alcohol sensor, and when it is determined that the alcohol concentration is smaller, the alcohol concentration is calculated as a predetermined alcohol concentration regardless of the detection voltage of the resistive alcohol sensor.

(Function) By configuring the present invention as described above, not only when the detection voltage of the resistive alcohol sensor is smaller than the first reference voltage Ipi1, but also when it is larger than the first reference voltage value, f
Even in a range smaller than the reference voltage value of JS2, the alcohol concentration can be calculated using the detection voltage of the resistive alcohol sensor, and when the detection voltage of the indirect sampling alcohol sensor is smaller than the second reference voltage value, the alcohol concentration is predetermined. By calculating the alcohol concentration as a predetermined alcohol concentration, the output voltage of the resistive alcohol sensor will have one value over the entire alcohol concentration range.

(Example) An example of the present invention will be described below in detail based on FIGS. 1 to 5.

In the figure, 1 is a resistance type alcohol sensor lO, which will be described later.
This figure shows an indirect sampling type alcohol sensor that supports this. 2.3 constitutes the alcohol sensors 1 and 10 of each of these methods, and includes a current-carrying electrode consisting of a pair of electrode plates spaced apart within the fuel vibrator a (see Fig. 7). The energizing electrode 2 is connected to the DC power source 4, and the other energizing electrode 3 is connected to the DC power source 4.
is connected to the DC power source 4 via a fixed resistor 5, and a constant voltage or current is applied thereto.

6.7 is the pair of current-carrying electrodes 2 and 3 in order to indirectly measure the potential difference of gasoline that exists between these flJIs.
A detection electrode consisting of another pair of electrode plates provided in between, the valley detection electrodes 6.7 being spaced apart from the energizing electrodes 2 and 3 by a predetermined distance, and facing each other with a predetermined distance from each other. It is arranged. Reference numeral 8 denotes a voltage detection device connected between the pair of detection electrodes 6 and 7 in order to detect the potential difference between the pair of detection electrodes 6 and 7. Here, as will be described in detail later, the output voltage V of the indirect sampling type alcohol sensor 1 rises in a region where the alcohol concentration C is low and reaches a maximum value V.
, , after reaching I, it has a voltage characteristic that decreases inversely proportional to the alcohol concentration C. An amplifier 9 is connected to the voltage detection device 8 for converting the detected voltage V having the above-mentioned characteristics into a transmittable output voltage (see FIG. 3).

On the other hand, IO is a resistive alcohol sensor that detects the alcohol concentration C in gasoline in the fuel pipe a, together with the indirect sampling type alcohol sensor 1, and the resistive alcohol sensor IO has a fixed resistor 5 similar to the prior art. A detection voltage v5 is derived from both ends of the sensor, and this detection voltage vs is output to an alcohol concentration calculating device 11, which will be described later.As shown in FIG. have.

Thus, in the embodiment, the indirect sampling type alcohol sensor l includes current-carrying electrodes 2 and 3, a DC power source 4, and a detection electrode 6.
．． 7 and voltage detection bags 5, 18, etc., the resistive alcohol sensor 10 includes current-carrying electrodes 2, 3, . Direct fItM,
It is composed of a source 4, a fixed resistor 5, and the like.

Next, reference numeral 11 denotes an alcohol concentration calculation device consisting of a CPU, etc. The input side of the alcohol concentration calculation device ii is connected to the amplifier 9 and the resistive alcohol sensor 10, respectively, and the output side is an injection! It is connected to the IL calculation device 13. Reference numeral 12 denotes a storage device such as a ROM or RAM connected to the alcohol concentration calculating device 11. In addition to the program shown in FIG. = 100% reference voltage value VSO (hereinafter referred to as first reference voltage value vso), resistive alcohol sensor 10
The reference voltage value VO (hereinafter referred to as the second reference voltage value V) of the indirect sampling type alcohol sensor I when the alcohol concentration C = 90% and the output voltage ■s reaches the maximum value V5vaa* is shown in FIG. A data map of output voltage V versus alcohol concentration C shown as a characteristic diagram is stored. The alcohol concentration calculation device 11 performs concentration calculation processing, which will be described later, based on data stored in the storage device 12, and then outputs an alcohol concentration signal C to the injection amount calculation bag rI13.

Here, regarding the second reference voltage value v0,
The output voltage V5 of the resistive alcohol sensor 10 takes a maximum value v8.1a in the high alcohol concentration region C. Therefore, the alcohol concentration C corresponding to the maximum value V 5sax
= 90% is based on 7ISi, and the voltage value when one indirect sampling type alcohol sensor l detects the alcohol concentration C = 90% is the reference voltage value V. This is set in advance. And indirect sampling type alcohol sensor l
Since the output voltage V becomes smaller inversely proportional to the alcohol concentration C, the output voltage V is the reference voltage value V when the alcohol concentration C is lower than 90%. For, V>V, and on the alcohol concentration side higher than C=90%, V>V. bawl.

Next, 13 is a fuel injection amount calculation device, and the injection amount calculation bag 2! At t13, the fuel injection amount is calculated from the alcohol concentration signal C, the engine speed N from the crank angle sensor 14, the intake air fjlQ from the air flow meter 15, etc., and the fuel injection signal C is output to the spray valve 16. It has become.

Moreover, 17 in the figure is an alcohol concentration meter.

Although the present embodiment is constructed as described above, the operation of the indirect sampling type and resistance type alcohol sensor 1.10 will be described first, and then the calculation process of alcohol concentration will be described.

A pair of current-carrying electrodes 2 and 3 of an indirect sampling type alcohol sensor l and a pair of detection electrodes 6 and 7 provided between these electrodes are connected to an alcohol-mixed gasoline d in a fuel vibrator a.
immersed in it. In this state, 5 pairs of current-carrying electrodes 2
．． 3, a constant voltage or current is applied from a DC power source 4. At this time, if the alcohol concentration C in the alcohol-mixed gasoline interposed between the current-carrying electrodes 2.3 is high, the resistance value is small, so the potential difference between the electrodes 2.3 becomes small; conversely, if the alcohol concentration C is low, , since the resistance value is large, electrode 2
, 3 becomes large.

Therefore, a voltage detection device 8 detects the potential difference between the current-carrying electrodes 2 and 3 by a pair of detection electrodes 6 and 7 interposed between the current-carrying electrodes 2 and 3. In this way, as shown in FIG. 4, it is possible to obtain a voltage characteristic in which the maximum value V, □ is reached in the low alcohol concentration region, and as the alcohol concentration C increases, the output voltage V decreases linearly. Alcohol concentration C in gasoline can be measured using voltage characteristics. When detecting the alcohol concentration C, the detection electrode 6.7 is not energized, so the electrode 6.7 is not affected by the polarization effect or relaxation effect. Even if the effect or relaxation effect appears, the detection electrodes 6.7 can accurately detect the potential difference between the current-carrying electrodes 2 and 3.

By the way, as mentioned above, the output voltage V from the indirect sampling type alcohol sensor rises once in the low concentration region and reaches the maximum value V +++ a x, and then the alcohol concentration C
It has a voltage characteristic that decreases in inverse proportion to . on the other hand,
The output voltage vs of the resistive alcohol sensor 10 has two values when the voltage value is larger than the first reference voltage value v3o, but when the voltage value is smaller than the first reference voltage value V5G, The voltage characteristic has only the l value with respect to the alcohol concentration C.

Therefore, in the embodiment, by utilizing the characteristics of the output voltages V, V, of the indirect sampling type alcohol sensor l and the resistance type alcohol sensor lO described above, the output voltage vs of the resistance type alcohol sensor lO is Both alcohol sensors l so that the l value.

The configuration is such that the alcohol concentration is calculated from the output voltages V and V of lO, which will be described below.

Therefore, this arithmetic processing will be described with reference to the program shown in FIG. First, when the engine is started and processing is started, the alcohol concentration calculation device 11 reads out the reference voltage value VIiO of tjS1 from the memory device 2t12.
(Step l). On the other hand, the alcohol calculation unit 2111 reads the alcohol concentration detection signal from the resistive alcohol sensor 10 as the detected voltage value vs (step 2).

Next, the alcohol concentration calculating device 11 calculates V from the detected voltage value v8 of the resistive alcohol sensor l and the reference voltage value Vso.
S>V,. Compare whether or not (step 3), rNO
When it is determined that the alcohol concentration is J, the detection voltage v5 of the resistive alcohol sensor lO is a detection voltage vs2 smaller than the first reference voltage value VSO, and the detection voltage VS2 has only 11a with respect to the alcohol concentration C. Using this detection voltage V52, a constant CK that depends on the alcohol concentration C is determined (step 4).

On the other hand, when it is determined in step 3 that it is rYEsJ, the process moves to step 5 and the alcohol concentration calculation device F! 111 is the second reference voltage value V from the storage device 12;

At the same time, the alcohol concentration detection signal is read from the indirect sampling type alcohol sensor 1 as a detection voltage value (Step 6), and the detection voltage value V and the second reference voltage value V are read. Tokaravkuv. Compare whether or not (Step 7)
. When it is determined that it is rNOJ, the detection voltage VS of the resistive alcohol sensor 10 is the detection voltage VS+ in the region before reaching the maximum value VS constant c
Determine K (step 4).

On the other hand, when rYESJ is determined in step 7, the detection voltage v5 of the resistive alcohol sensor is the maximum value V
Since the detected voltage Vg is rapidly decreasing from 5IIIIN, the process moves to step 8, where the detected voltage Vg is held, and a constant CK for setting the alcohol concentration C=90%, for example, is determined.

In this way, the detected voltage, v5, is a constant voltage reference value VS
Constant CK and voltage reference value VS that depend on the alcohol concentration C when it is below 0 (alcohol concentration C when it exceeds l)
After determining the constant of =90%, the process moves to step 9 and calculates the fuel injection amount T based on the CK.

As described above, according to the embodiment, the resistive alcohol sensor 1
Since the output voltage v5 of 0 always has a value of 1 even if it is larger than a certain reference voltage value VSO, the output voltage vs
has good linearity and therefore can be used with high precision and a wide range of applications.

In the embodiment, the output voltage vs of the resistive alcohol sensor lO reaches its maximum value v at about 90% of the alcohol concentration C.
8. □The maximum value V Smmz for the alcohol concentration C is the resistance type alcohol sensor 1.
Of course, it depends on the performance of 0.

Further, in the calculation process of alcohol concentration, step 3 is a specific example of the first determining means of the present invention, and step 7 is a specific example of the second determining means of the present invention, but the present invention does not apply to these specific examples. It is not limited.

Furthermore, although alcohol-mixed gasoline was exemplified as the alcohol-mixed liquid in the examples, the present invention can also be applied to other alcohol-mixed liquids.

〔Effect of the invention〕

The present invention has been described in detail above, and the detection voltage of the resistive alcohol sensor is larger than a predetermined reference voltage value,
Moreover, when the detection voltage of the indirect sampling alcohol sensor becomes smaller than a predetermined reference voltage value, the resistance alcohol sensor outputs a predetermined alcohol concentration signal regardless of the detection voltage of the resistance alcohol sensor. Since the alcohol concentration measuring device is configured to take one value over the entire range of , it is possible to provide an alcohol concentration measuring device with good output voltage linearity, high accuracy, and a wide range of use of detection results.

[Brief explanation of the drawing]

1 to 5 relate to embodiments of the present invention. Figure 1 is a circuit diagram that integrates an indirect sampling type alcohol sensor and a resistance type alcohol sensor, Figure 2 is an explanatory diagram of the configuration of the indirect sampling type alcohol sensor, and Figure 3
The figure shows a system configuration diagram when an alcohol concentration measurement device is applied to a fuel injection u control device, Figure 4 is a characteristic diagram showing the relationship between alcohol concentration and output voltage, and Figure 5 shows how fuel injection amount is determined from alcohol concentration. Flowcharts showing the calculation process, FIGS. 6 to 9 relate to the prior art, FIG. 6 is a diagram showing the relationship between the air-fuel ratio and the alcohol concentration, and FIG. FIG. 8 is a diagram showing the relationship between alcohol concentration and detection resistance, and FIG. 9 is a characteristic diagram showing the relationship between alcohol concentration and output voltage. 1-...Indirect sampling type alcohol sensor, 10-
...Resistive alcohol sensor, 11--Alcohol concentration calculation device, 12--Storage device, 13--Injection amount calculation device. Figure 4 Alcohol 1 degree C (■/,) Figure 4

Claims (1)

[Claims] a pair of current-carrying electrodes that are spaced apart and facing each other in an alcohol mixed liquid and to which a constant voltage or current is applied; an indirect sampling type alcohol sensor that has a pair of detection electrodes installed and detects alcohol concentration using a potential difference between the detection electrodes; and a resistor that detects alcohol concentration from a resistance value in the alcohol mixed liquid. a first determination means for determining whether the detection voltage of the resistance alcohol sensor is smaller than a first reference voltage value when alcohol in the alcohol mixed liquid is at a predetermined high concentration; a second determination means for determining whether or not the indirect sampling type alcohol sensor has a voltage higher than a second reference voltage value preset with reference to the alcohol concentration corresponding to the maximum value of the detection voltage of the resistance type alcohol sensor; and when the first determining means determines that the detected voltage of the resistive alcohol sensor is smaller than the first reference voltage value, calculates the alcohol concentration using the detected voltage of the resistive alcohol sensor; When the first determining means determines that the detected voltage of the resistive alcohol sensor is greater than the first reference voltage value, the second determining means determines that the detected voltage of the indirect sampling alcohol sensor is higher than the first reference voltage value. 2, and if it is determined to be high, the alcohol concentration is calculated using the detection voltage of the resistive alcohol sensor, and if it is further determined to be smaller, the alcohol concentration is calculated using the detected voltage of the resistive alcohol sensor. An alcohol concentration measuring device configured to calculate a predetermined alcohol concentration regardless of a detection voltage.